FIG. 1 shows a prior art electronic communication system 1 that is used to securely transfer documents from a sender 2 to a recipient 3 by way of a server 5. Sender 2 is a personal computer within which a plaintext document 6 is created. The transmission of the contents of document 6 is accomplished via a secure socket layer (SSL) channel 7. Accordingly, as is known in the art, as part of the SSL transmission mechanism the document 6 is not sent in plaintext but is encrypted and transmitted as an encrypted document 8.
Server 5 decrypts the encrypted document 8 and stores the plaintext document 6 in associated memory 9. The server 5 then electronically notifies a recipient computer 3 that the plaintext document 6 is available at the server 5 for downloading and/or viewing by the recipient computer 3. The recipient computer 3 transmits a recipient password to the server 5 in order to gain access to the document 6. Server 5 has stored in memory 9 the passwords for any recipient and therefore is able to verify whether the received password is the one associated with the recipient to which the server 5 provided notification. If verification is successful, server 5 downloads the contents of document 6 as an encrypted document 11 via an SSL channel 12 in the same manner as discussed above for the initial transmission of the document contents from the sender 2 to the server 5. Upon receipt of the encrypted document 11 at the recipient computer 3, it is decrypted using conventional browser technology so that it can be stored at the recipient computer 3 as document 6 and subsequently printed.
While the system 1 provides some security by using the SSL channels (7, 12) to securely transmit the contents of the document 6, it still has inherent security risks associated therewith. For example, system 1 requires complete trust that the server 5 operation is sufficient to protect the document 6 that is stored in memory 9. Access to the document 6 at the server may be possible thereby compromising the security of document 6. Further, even assuming that document 6 could be encrypted by server 5 and stored in an encrypted form, the server 5 still has the capability to decrypt the document into a plaintext and viewable format. Thus, relative to the server 5, the contents of the document 6 can always be made available.
Additionally, recipient access to the document 6 at server 5 is accomplished by having knowledge of a recipient's password. Anyone with the password can gain access to the document 6. Moreover, since many password systems lock out access once a predetermined number of unsuccessful passwords have been entered, a third party could deny legitimate access to a document by an intended recipient simply by entering incorrect passwords into the system. Accordingly, a more robust and secure document viewing system is needed.